Apparatus for grading materials.



H. K. HITOHOOGKJ APPARATUS FOR GRADING MATERIALS.

API LIUATION TILED JULY 19, 1907. 934,61 1 Patented Sept. 21,1909.

INVENTOR HALBERT K. HITCHCOCK, 0F TAEENTUM, PENNSYLVANIA.

APPARATUS FOR GRADING MATERIALS.

Specification of Letters Iiatent. Pi trgmted Sept, QL'TQQQ),

Application filed July 19, 1907. Serial No. 384,838. J

To all whom it may concern:

Be it known that I Ilr-xnnnn'r K. Hrroncook, a citizen of the United States, residing at Tarentum, in the county of Allegheny and State of l.ennsylvania,have invented certain new and useful Improvements in Apparatus for Grading Materials, of which i the following is a specification.

My invention relates to apparatus for separating finely divided material comprising particles having different physical characteristics-into grades each of which includes those particles having similar physical characteristics, and is applicable, for example to the grading of material used as abrasives such as are employed in the grinding of glass or other substances, thebinders used in ceramics, and in fact-to the gradin of an finely divided material whatever, w ich it 1s desired to separate into grades. The invention has for its rimary objects: the provision of a simp e and compact apparatus wherein the separation of the divided material into various grades required may be accomplished more conveniently and rapidly than has been heretofore the case; and. to provide an apparatus in which the separation into grades is accomplished with cer-' tainty'and accuracy and wherein there is no waste of material. One embodiment of the invention is illustrated inthe accompanying drawings, wherein:-

The figure is a side elevation of the apparatus partially broken away.

For the sake of definite illustration, the apparatus is shown and hereafter described as applied to-the grading of the abrasives used 1n glass grindmg, but it will be understood that the .a paratus is applicable to the grading of any nely divided material whatsoever, and that the scope of invention is not limited to the grading of an particular material, but is coincident wit the statement of invention and claims. Briefly stated,the apparatus comprises a tank having an admission opening at the bottom and means for giving an upward flow of liquid through the admlssion opening, together with a series of exit passages at different levels on the. tank for conducting away the various strata of fluid. The fluid asses upwardly from the bottom of the an; at a constantly decreasing velocity thereb counterbalancing the normal downwar velocity of the particles of material when falling in the liquid, and holding them in suspension at predetermined positions in the tank, which positions depend upon the upward veloclty of 1 the weight of the particles. The particles in which the ratio of the weight to the resistance'of the liquid is largest take the lowest positions, asthe normal locit of a particle through the water depenc s upon this ratio, which ratio in particles ofthe same shape and density increases with the size of the particles. The larger, denser and more com act particles thus come to a position of equi ibrium in a stratum in the bottom of the tank where the upward velocity is greatest, while the other particles arrange themselves in a series of strata, the

ratios of weight to resistance of the particles composing which strata, decrease as the distance from the bottom of the tank increases. The apparatus illustrated is designed for the mixture of material and water into the bottom of the tank is continuous and the outflow from the various discharge pipes is also continuous instead of intermittent as in the structure shown. In this operation the pipes 2 3 4 and 5 are extended into the tank and provided with small openin s 20, so that a very small percentage of tfie liquid flowing in at the bottom vof the tank the combined capacity of these openings being small as compared with the capacity of the admission tube 21 and the bulk of liquid passing out at the overflow pipe 6 Th1s is obviously desirable in order to prevent an undue roportion of the finer material from being diverted during its upward movement and being discharge at an opening below its position of equllibrium. The steam injector 12 is provlded, which injector forces the mixture of material and water upward through the admission tube 21 from the pit shown. In this form of apparatus the character of the original mixture has little orno effect upon the various grades, as the proportion of material to water is so small that any change in interstitial space and resultant change in velocity due to a change in the character of the material is very slight.

Having thus described m invention and illustrated its use, what I c aim as new and desire to secure by Letters Patent is the following the liquid, the resistance of the particles and downward vea continuous operation wherein the flow of is discharged at such discharge openings,

-1. In combination, a'grading tank with downwardly converging sides and having an admission passage to the lower portion v -fthereof and having a plurality of discharge ity of the admission passage, and'means for securing a continuous flow of liquid containing in suspension divided material to be graded up through such passage and the tank.

2. In combination a grading tank with downwardly converging sides and having an admission passa e to the lower portion thereof and a plurahty of discharge pipes at difierent levels havin passages therein of small-combined capaclty as compared with the capacity of the admission passage, and of passages at diflerent levels of small com-- med capacityfas compared with the capac' divided material to begraded up through the admission passage and the tank.

-3. In combination, a grading tank with downwardly converging ides and having an 1 admission assage to the lower-portion thereof, and a p urality of discharge pipes at different levels having their ends projecting inward past the inside surface of the tank and having passages of small combined capacity as compared with the capacity of the admission passage, andmeans 'for se-.

curing a continuous flow of liquidcontaining in suspension divided material to be graded up through the admission passage and the tank. 7 J

\ In testimony whereof I have hereunto signed my name in thepresence of thetw'o subscribed witnesses. .HALBERT K.HITCHCOCK.

Witnesses:

F. E.,GA1T1IER, v ARCH-WORTH MAnnN. 

